1. Field of the Invention
The present invention relates generally to the field of mass storage systems, and more particularly to high capacity systems having improved data security features and configuration options.
2. Description of the Related Art
With the explosion of electronic data in the information age, it is important that information processing systems be provided with fault tolerant data handling capabilities, including data redundancy to ensure that critical data is preserved in the event of a system failure. Mass storage devices such as hard drives, tape drives, and rewritable optical drives are used for providing backup of large amount of data. Hard drives are by far the most popular format for mass data storage, especially in relatively smaller information processing systems, e.g., local area networks.
So called RAID (which stands for Redundant Array of Independent Disks) systems have been designed to provide improved performance, increased capacity and increased level of data redundancy demanded by, for example, data processing, document imaging, data security and networking applications. Some RAID systems have one or more arrays of user removable data storage modules. For example, the RAIDbank Pro Disk Arrays system developed by the assignee of the present invention, MicroNet Technology, Inc. in California, includes drive bays for up to six removable disk drive modules (of the `hot` swappable type) and two removable power modules in a system cabinet. Data transfer from the host computer system to the MicroNet RAID system is via a SCSI (which stands for Small Computer Systems Interface) port. A utility software installed at the host computer facilitates user configuration of the RAID functions programmed into the firmware in the RAID system. For example, the user can select the appropriate RAID level supported by the system, based on priorities including disk capacity, data redundancy and fault tolerance in the event a drive fails, and disk performance. The MicroNet RAIDbank Pro system may be configured so that data on a failed drive can be reconstructed by a process known as data rebuilding, which process may be invoked either automatically by the RAID system control without user intervention or manually by a system administrator. The MicroNet RAID system includes, in addition to disk failure detection, built in features such as system temperature detection, power failure detection, power surge protection, and alert alarms related thereto. A more detail description of the structure and functionality of the device may be found in the User Guide for the MicroNet RAIDbank Pro Disk Arrays system published by the assignee of the present invention, MicroNet Technology, Inc. (August 1995; Part No. MA4268), which is fully incorporated by reference herein.
There are drawbacks in the prior art RAID systems. For example, the prior art Systems do not prevent removal of a wrong drive by a user. A wrong drive may be removed inadvertently in the event of drive failure. This could have disastrous consequences. Losing a second drive in a redundant RAID system will cause all the data to be lost.
Further, the prior art failure detection alert functions provide only local alarms, which require the system administrator to be present at the system site in order to be able to determine the specific failure mode. Further, it is desirable to provide greater flexibility in the configuration of the storage arrays to facilitate more efficient use of the RAID system mass storage capability.